Electric induction-furnace.



0. W.;S61JERBERG.

ELEGTRIU INDUGTION FURNAGE. APPLICATION FILED MAY15, 1909.

954,827. I Patented Apr. 12, 1910.

j/fizhwded/ I k/W U. QUi/U, 6m W 1 1 CARL WILHELM sbDERBERG, OF SKI, NEAR CHRISTIANIA, NORWAY.

ELECTRIC 'INDUCTION-FURNAGE.

Specification of Letters Patent.

Patented Apr. 12, 1910.

Application filed May 15, 1909. Serial No.,496,21

-To all 'uihom it may concern:

Be it known that I, CARL WILHELM Sousa- BERG, a subject of the King of Norway, residing at Ski, near Ohristiania, Norway,'have invented certain newand useful Improvements in Electric Induction-Furnaces; and

I do hereby declare the'following to be a full, clear, and exactdescription of the invention, such as-will enable others skilledin.

the art to which it appertains to make and use the same, reference being had to the accompanying drawings, andto letters or figures of reference marked thereon, which form apart of this specification.

My invention relates to electric induction furnaces of the transformer type. An electric induction furnace theoretically consists of .a transformer with short circuit in its secondary coils, the latter mostly consists of one or more liquid metal baths, which replace the coils, the ohmic resistance of which is so adjusted, that a suitable load obtained. It is important, in order to obtam a minimum leakage of the power lines, that the disk transformers have the coils so distributed, that the whole number-ofampore-turns is not concentrated to one coil.

The object of my invention is to provide an induction furnace of the disk-transformer type, in which this electrical feature as well as means for facilitating the metallurgical operations are embodied.

In the accompanying drawing a constructional form of apparatus is shown in which:

Figure l-is a horizontal section of the apparatus on the line D-E of Fig. 2 and Fig. 2 is a vertical, section of the same on the line A'B in Fig. 1, a

The primary windings are distributed on fOlJlT'COllS as a a, inclosing both of the vertical parts I), and b of the iron core.- The secondary armature consists of a metal bath m 1%,, contained in a hearth m arrangedbetween the primary coilsand formed with an intermediate portion, and two semi-annular channels 6,, (2,, which together with the intermediate portion inclose both of the vertical pieces of the iron core. By the-arrangement of four coils theleakage of the ower linesis cut down to about one fourth 0 what it would otherwise have. been under similar.

' the core.

circumstances, in known constructions of induction furnaces of the disk-transformer type having iron cores.

The lower primary coils are cooled by currents of air which pass through channels ti (i, in the foundation of the furnace which may be of masonry or any suitable material as the effect of the intensity of the current is proportional to its square; the above mentioned cooling diminishes the resistance and the intensity of current is increased. The

eificiency of the furnace per unit of time thus increases, an advantage which is the more important in this construction, because the coils incloseboth of the vertical legs of the transformer. v

. In order to facilitate the metallurgical operations, which are rendered difiicult on.

account'of the primary coil covering part of the'metal bath the extended parts of the bath are situated outsideof the current carrying parts of the bath and 'not covered by the primary coils. Such channels, have been used in some prior constructions, butnever in furnaces of the disk-transformer type for the above mentioned purposes of providing working space, the metallurgical operations, the feed, and the treatment of the slag are facilitated and repairs may beeasily made without removing any part of the primary coils of the furnace.

I claim 1. In an electric induction furnace, an iron core, a hearth having an intermediate portion and semi-annular ends surrounding the portions of the .core that pass through the hearth, a primary coil system comprising two disk coils above the hearth surrounding those portions of the core extending through the hearth, said disk coils beingin close proximity to the hearth and coveringonly'i the semi-annular portions of the bath inthe termediate portion of the hearth open, and

disk coils below the hearth alsosurrounding 2..' In an electric induction furnace, an iron core, a hearth having an intermediate portion and semi-annular. ends surrounding the portions of the core thatpass through-the earth, a primary 'coil system comprising two disk coils above the hearth surrounding to permit a current of air to pass around the. 10

those portions of the core extending'through lower coils. I

the hearth, said disk coils being in close In testimony that I claim the foregoing as proximity to the hearth and covering only my invention, I have signed my name in .5 the semi-annular portions of the bath in the presence of two subscribing Witnesses.

hearth, thereby leaving the bath in the inter- CARL WILHELM SCDERBERG, mediate portion of the heerthopen, and disk Wit coils mounted below the hearth in channels t, HENRY BORDEWICH,

formed in the furnace, said channels adapted M. ALGEB. 

